This grant will seek to develop a methodology that will allow us to test whether a promising new class of drugs for Alzheimer's disease is having the desired effect in the human brain. This methodology will allow pharmaceutical companies to make informed decisions about which drugs to advance into late stage clinical trials, and to optimize dosing and administration schedules based on pharmacodynamic response. C2N Diagnostics has licensed the platform technology from Washington University to carry out the company's stable isotope labeling kinetic (SILK) assay. This assay is used to measure production and clearance rates of proteins in the brain. Previously, this methodology has been applied to measuring production and clearance of total A2 from the brain, and evaluating the biologic activity of certain compounds in clinical development for the treatment of Alzheimer's. To measure the biologic activity of an emerging class of compounds, gamma-secretase modulators, we need to be able to measure the production and clearance of the individual A2 isoforms, specifically A2 38, 40 and 42. The experiments proposed in this grant will develop this methodology in Phase I of this grant. In Phase II, the methodology will be applied to a small patient study. Applying the technology to a proof of concept human study will greatly facilitate commercialization of the technology. Further, this technology will greatly enhance our understanding of how AD metabolism plays a role in the pathogenesis of the disease. PUBLIC HEALTH RELEVANCE: Alzheimer's disease is a growing problem with an estimated 5 million people currently affected in the US. There are currently no disease modifying drugs approved for AD, in part due to a paucity of relevant tools to measure biologic activity and clinical efficacy for these types of drugs. The proposed experiments are intended to allow C2N to help pharmaceutical companies optimize the quality of their drug development efforts and to expedite bringing promising disease modifying treatments to the clinic.